Difference between Hermetic, Semi-Hermetic And Open Compressor - Advantages and Disadvantages

Hermetic Compressor

In a hermetic sealed, compressor and driving motor coupled to the same shaft, and are enclosed in a common rigid casing made of welded steel. This type of compressor eliminates the use of Crankshaft Seal, which is used to prevent leakage. This makes whole the compressor and motor as a single compact unit makes it easy to handle. Basically, hermetically sealed compressors are air tight and ensure no leakage of the working fluid to outside.

Hermetically sealed compressor widely used for small motor compressor combination used in a domestic refrigerator, freezer and air conditioner.

Advantages and disadvantages of hermetic seal compressor

Advantages

• Leak proof / completely sealed housing - There is no route for gas to leak out this system. There are no shaft sales since both compressor and motor sealed in the same casing.
• Portable compressor and motor act as a single unit.
• No belt pulley coupling arrangement - No need disassembles the compressor from the motor to move the system from one place to another.
• Since there is no belt coupling or crankshaft, cost involved with the maintenance is less.
• It is compact; they require small space.
• Lubrication is simple; there is no external lubrication is required.
• It is less noisy
• Installation of hermetic sealed compressor is very easy.

Disadvantages

• They are not intended to repairing since the moving parts are inaccessible if there is any problem you need to do you replace the whole unit.
• Burnout winding can contaminate entire system.
• Only electric power sources can run this unit.

The semi-hermetic compressor also encloses the motor compressor by Common Housing. It prevents the leakage of the fluid. In a semi-hermetic, the casing is bolted together instead of rigidly welding. It offers limited serviceability; casing can be open to repair motor and other components.
In this type, compressor and motor working as two separate units, and they have a distinct casing for both of them. The compressor is connected to the motor by a belt or crankshaft. Open type compressors are not leak proof they are more susceptible to leak. They rely on shaft seals in order to prevent leakage of working fluid and then to retain the internal pressure. The shaft seal required to lubricate otherwise seals begins to leak.

Advantages of open compressor

• They can be driven from a non-electric power source such as turbine, IC engine.
• Compressor and motor are accessible to repair in case of failure.
• Servicing is easy and cheap

Disadvantages of open compressor

• Noisy operation
• Not leak proof they need shaft seals to prevent leakage lubrication required at sealing to maintain Pressure.
• They are not compact.

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